Method of joggling



Nov. 25, 1952 L. J. SELF METHOD OF JOGGLING Filed May 31, 1949VINVENTOR. LEW/3 .1. SELF 8 mew ff Patented Nov. 25, 1952 UNITED METHODOF J OGGLING Lewis .1. Self, Inglewood, Calif., assignor to NorthAmerican Aviation, Inc.

Application May 31, 1949, Serial No. 96,366

1 Claim. 1

This invention pertains to apparatus for joggling sheet metal such asDuralumin used in airplane work.

The invention is more particularly adapted for use with machines of thetype shown and described in Patent No. 2,357,027 in which material isstretched to between its yield point and ultimate strength and thenwrapped around a die while in that condition to thereby shape thematerial to the contour of the die.

In aircraft work it has been found necessary to provide the formed partwith indentations and recesses for various purposes. These have beenprovided largely by hand, or by separate joggling machines. When sojoggled, there is danger of inducing undesirable stresses in thematerial and particularly when parts of the material are stressed toabout its ultimate strength while other parts are stressed to onlyslightly above their yield points. Also, inaccuracies have been found toobtain when joggling is done separately from the forming operation.

Accordingly, it is an object of this invention to provide an arrangementwhereby joggling can be obtained as a part of the stretch formingoperation.

It is a further object of this invention to provide a jogglingarrangement which may be used in combination with a stretch formingmachine.

It is yet another object of this invention to provide a joggling devicewhich can be used with existing equipment without damage thereto.

Other objects of invention will become apparent from the followingdescription taken in connection with the accompanying drawing, in whichFig. l is an elevational view, partly in section, taken along the lineI-I of Fig. 2; and

Fig. 2 is a plan view taken along the line 2-2 of Fig. 1.

Referring to the drawing, jaws such as I are adapted to grip the ends ofmaterial 2, stretch the same to above its yield point, associate thestretched material with a die 3 and then wrap it about die 3 to conformto the contour of the die, as more fully explained in Patent No.2,357,027. According to the present invention the die is provided withpredeterminately located and sized recesses or contours, such as 4 and5, representing conformations desired to be obtained in the finishedarticle. In the particular embodiment of the invention, material 2 is achannel section adapted to be stretch formed on die block 3, which dieblock may be provided with recesses 4a and 5a in the base of the channelmember corresponding to recesses 4 and 5. It is to be understood, ofcourse, that the die may be provided with other contours and shapes, aswell as other types of recesses, and that the section may be of anydesired shape.

According to the present invention a joggle die 6 having a preselectedcontour conforming to the recess, such as 4, is adapted to be actuatedby piston I of a hydraulic arrangement 8 which in turn is connected to asource of fluid under pressure by hose lines 9 and II]. A pin II adaptedto be received in hole I2 of die 3 is connected to the hydraulicarrangement by yoke I3 or the like so as to receive directly thejoggling force. This avoids any bending strain on the die 3 and permitsthe invention to be used with present arrangements. Die 3 may beprovided with a series of holes I2 adapted to receive pin I I at suchpoint where a joggle operation is to be performed. A single hole I2 maybe used where the contour of the die is an are.

In the operation of the device a piece of material such as 2 is grippedby jaws I, stretched to above its yield point but below its ultimatestrength, and then associated with and wrapped around die 3. With thematerial in its stretched condition, the pressure exerted through thehydraulic system of jaws I is relieved, but the jaws nevertheless holdmaterial 2 in stretched position. Thereupon the joggle apparatus formingthis invention is arranged with pin II in a selected opening I2, die 6is attached to piston 1 in any suitable manner, such as by hooks I4, andhydraulic pressure is applied by suitable controls (not shown) to causepiston I to force die 6 against material 2 and into a preselectedrecess, such as 5. This provides a joggled indentation or the like inmaterial 2 while the material is held by jaws I after having beentensioned to above its yield point. This avoids spring-back, undesirablestressing of the material, and inaccuracies such as are obtained whenthe material is joggled separately after the stretch forming operation.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample only and is not to be taken by way of limitation, the spirit andscope of this invention being limited only by the terms of the appendedclaim.

I claim:

The method of joggling material comprising the steps of gripping saidmaterial; exerting a stretching force on said material above the yield 3point thereof; associating said material while so stretched with a diehaving a recess therein; wrapping said material about said die; relaxingsaid stretching force; and forcing a second die against said materialand into said recess for thereby providing a joggled indentation in saidmaterial.

LEWIS J. SELF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Fetcher -2 Mar. 5, 1918 Number NumberNumber Name Date Jolstad Mar. 29, 1927 Misfeldt Nov. 24, 1942 SeifriedAug. 29, 1944 Lindsey Mar. 2, 1948 Hochreiter July 27, 1948 Brennan Oct,18, 1949 Leutheuser Dec. 6, 1949 FOREIGN PATENTS Country Date AustraliaMar. 22, 1927 Germany Mar. 27, 1930

